The present invention relates to boxes or other receptacles for the safe containment of exposed electrical circuits.
Large polyphase electrical motors are common in many industries including but not limited to the nuclear power industry. Depending upon their use and construction, such motors can require hundreds and even thousands of volts of electrical power for operation. Such motors are often or typically coupled with their high voltage power supplies through protective cabinets or similar enclosures. Such cabinets not only protect the exposed, live or "hot" electrical connections from adverse environmental conditions, they also protect personnel who may have to work in the vicinity of such enclosures from contact with such connections. The cabinets may be safety interlocked or under controlled access to provide further protection from inadvertent openings while the cabinet is energized.
Because of the hazards involved, workers may be required to don special protective gear when working in an energized cabinet. In the nuclear power industry, workers not involved in actual work in the cabinet may, nevertheless be evacuated from the vicinity of the cabinet for safety reasons. Even with protective gear, exposed wires and connections in such cabinets can pose a danger of severe injury and even death to workers. Also, inadvertent contact with live connections in the cabinet could trip the associated motor and possibly cause severe damage to the equipment.
In certain instances, desired maintenance procedures require access to the live connections within an energized motor cabinet. For example, U.S. Pat. No. 5,521,482 to Lang et al., incorporated by reference herein in its entirety, discloses methods and apparatus for determining mechanical performance of polyphase electrical motor systems. These require measurements of the currents and voltages applied to such motors. The measurements are normally taken by clip-on connectors and/or probes, which are attached to energized elements within the cabinet.
These routine maintenance functions can constitute a danger to the operation of the equipment and to the personnel performing the functions.